Three-dimensional Mechanics Analysis Of Immersed Tunnel Under Fire Temperature Fields

Hong Kong-Zhuhai-Macao Bridge project is the super-engineering in the worldwhich first involves “the three places” in China, the main project includes an immersedtunnel crossing Lingdingyang waterway, it is currently the longest (5664m), deepestdepth (50m), largest (six lanes) and heaviest single element (75000T)underseaimmersedtunnel in the world, but also the most sophisticated technology, higheststandard sea tunnel engineering in China’s traffic construction history,and the designand construction difficulty is premier in the world.Hong Kong-Zhuhai-Macao undersea immersed tunnel is located on the base tankof sea bed, which has two-hole and a gallery with single lining structure in thetransverse, element+composite joints tandem composite structure in the longitudinal,these special external conditions and internal structure forms is more sensitive to fire.Once fire happened, the damage of element and joint would occur, which it is difficultto repair, and has tremendous impact in structural waterproofing and safety service.Based on this, this paper relies on the Hong Kong-Zhuhai-Macao Bridge project,studying on fire scene design,element structure’s three-dimensional temperature field,element and joint’s high temperature stress and injury,the details are as follows:①Hong Kong-Zhuhai-Macao immersed tunnel fire sceneBased on the characteristics of the immersed tunnel cross-section, through1:1fullscale fire experiments and data analysis, in reference to the road tunnel fire scenario,it establish a complete fire scenarios of the Hong Kong-Zhuhai-Macao immersed tunnelwhich with time, spatial variation.②The structure temperature field distribution of immersed tunnel elementThrough establishing three-dimensional numerical model of temperature field offire, taking into account different temperature levels (600℃,900℃,1200℃) andRABT curve, it got the law of temperature spread and distribution of immersed tunnelstructure.Discussingthe thermal insulation of magnesium fire board for element, and theresults show that half section fire board layout proposal can meet the fire resistancerequirements.③The mechanical behavior of element structure athigh temperatureOn the basis of consideration of contact between the element (segments), throughestablishingthree-dimensional thermal mechanical coupling model under (non) insulated condition of immersed tunnel, it got the law of displacement, stress distribution andinjury depth of element and segment in two conditions, and for the geometriccharacteristics of the element joint, found the law of the maximum depth of damagelocation.④Mechanical behavior of jointunder high temperatureThrough establishingimmersed tunnel element joint, segment joint analysis modelsunder (non) insulated condition, including element joint GINA water stops and shearkey, it got the law of displacement of element joint and shear variation of two kinds ofjoints at different heating curve, and pointed out that fire has great influence on shearkey at location of the fire-side interior wall and roof.